Proliferating cell nuclear antigen (PCNA) as a proliferative marker during embryonic and adult zebrafish hematopoiesis

Hexafluoropropylene oxide trimer acid, a perfluorooctanoic acid alternative, induces cardiovascular toxicity in zebrafish embryos

As an increasingly used alternative to perfluorooctanoic acid (PFOA), hexafluoropropylene oxide trimer acid (HFPO-TA) has been widely detected in global water environments. However, little is known regarding its toxic effects on cardiovascular development. Here, zebrafish embryos were treated with egg water containing 0, 60, 120, or 240 mg/L HFPO-TA. Results showed that HFPO-TA treatment led to a significant reduction in both larval survival percentage and heart rate. Furthermore, HFPO-TA exposure caused severe pericardial edema and elongation of the sinus venous to bulbus arteriosus distance (SV-BA) in Tg (myl7: GFP) transgenic larvae, disrupting the expression of genes involved in heart development and thus causing abnormal heart looping. Obvious sprouting angiogenesis was observed in the 120 and 240 mg/L exposed Tg (fli: GFP) transgenic larvae. HFPO-TA treatment also impacted the mRNA levels of genes involved in the vascular endothelial growth factor (VEGF) pathway and embryonic vascular development. HFPO-TA exposure significantly decreased erythrocyte number in Tg (gata1: DsRed) transgenic embryos and influenced gene expression associated with the heme metabolism pathway. HFPO-TA also induced oxidative stress and altered the transcriptional levels of genes related to cell cycle and apoptosis, inhibiting cell proliferation while promoting apoptosis. Therefore, HFPO-TA exposure may induce abnormal development of the cardiovascular and hematopoietic systems in zebrafish embryos, suggesting it may not be a suitable or safe alternative for PFOA.

Syringic acid guards against indomethacin-induced gastric ulcer by alleviating inflammation, oxidative stress and apoptosis

The purpose of this study was to evaluate the effects of syringic acid, an anti-oxidant, on indomethacin induced gastric ulcers in rats. Experimental groups were control, ulcer, ulcer treated with 20 mg/kg esomeprazole (a proton pump inhibitor that reduces acid secretion), and ulcer treated with 100 mg/kg syringic acid. Rats were pretreated with esomeprazole or syringic acid two weeks before ulcer induction. Our histopathological observations showed that either syringic acid or esomeprazole attenuated the severity of gastric mucosal damage. Moreover, syringic acid and esomeprazole pretreatments alleviated indomethacin-induced damage by regulating oxidative stress, inflammatory response, the level of transforming growth factor-β (TGF-β), expressions of COX and prostaglandin E2, cell proliferation, apoptosis and regulation of the NF-κB signaling pathway. We conclude that either esomeprazole or syringic acid administration protected the gastric mucosa from harmful effects of indomethacin. Syringic acid might, therefore be a potential therapeutic agent for preventing and treating indomethacin-induced gastric damage.

A pattern recognition receptor CgTLR3 involves in regulating the proliferation of haemocytes in oyster Crassostrea gigas

Toll-like receptors (TLRs) are expressed on various immune cells as key elements of innate and adaptive immunity, and they also play significant roles in regulating cell proliferation and differentiation. In the present study, the binding activity of CgTLR3 to PAMPs and CgMyD88-2, and its role in mediating the proliferation of haemocytes was investigated. The recombinant proteins of the extracellular six LRR domains (rCgTLR3-LRR) and intracellular TIR domain (rCgTLR3-TIR) of CgTLR3 were obtained respectively. rCgTLR3-LRR exhibited binding activity to lipopolysaccharide (LPS), peptidoglycan (PGN), mannan (MAN) and Poly (I:C), with the highest affinity for LPS. While rCgTLR3-TIR displayed binding activity to the recombinant protein of rCgMyD88-2, with KD value of 7.22 × 10-7 M. The CgTLR3 mRNA and protein were detected in three subpopulations of oyster haemocytes, and they were mainly concentrated in granulocytes, which was 7.27-fold (p < 0.05) of that in semi-granulocytes and 8.51-fold (p < 0.01) of that in agranulocytes. The percentage of CgTLR3 positive cells (FITC+ haemocytes) in granulocytes was 4.45-fold (p < 0.01) and 2.57-fold (p < 0.05) of that in agranulocytes and semi-granulocytes, respectively. After Vibrio splendidus stimulation, the mRNA expression level of CgTLR3 in haemocytes significantly upregulated at 6 h and 12 h, which was 2.93-fold (p < 0.05) and 4.15-fold (p < 0.05) of that in the control group. After the expression of CgTLR3 was inhibited by the injection of si-CgTLR3, the expression levels of transcription factors associated with hematopoiesis (CgGATA, CgRunx), cell cycle-related genes (CgPCNA, CgCDC-45, CgCDK-2), the agranulocyte marker CgCD-9, the granulocyte marker CgAATase, and the inflammatory factor CgIL17-1 significantly decreased (p < 0.05) after the V. splendidus stimulation, which were 0.43-fold, 0.83-fold, 0.48-fold, 0.44-fold, 0.53-fold, 0.7-fold, 0.62-fold, and 0.47-fold of that in NC + V. s group in vivo, respectively. Meanwhile, the percentage of EdU+ haemocytes in si-CgTLR3+V. s group was significantly reduced by 0.54-fold (p < 0.05) compared to the control group (2.7%). These results collectively indicated that CgTLR3 was involved in modulating the proliferation of haemocytes by regulating the expression of proliferation-related genes and inflammatory factor in oyster C. gigas.

Unraveling DNA Repair Processes In Vivo: Insights from Zebrafish Studies

The critical role of the DNA repair system in preserving the health and survival of living organisms is widely recognized as dysfunction within this system can result in a broad range of severe conditions, including neurodegenerative diseases, blood disorders, infertility, and cancer. Despite comprehensive research on the molecular and cellular mechanisms of DNA repair pathways, there remains a significant knowledge gap concerning these processes at an organismal level. The teleost zebrafish has emerged as a powerful model organism for investigating these intricate DNA repair mechanisms. Their utility arises from a combination of their well-characterized genomic information, the ability to visualize specific phenotype outcomes in distinct cells and tissues, and the availability of diverse genetic experimental approaches. In this review, we provide an in-depth overview of recent advancements in our understanding of the in vivo roles of DNA repair pathways. We cover a variety of critical biological processes including neurogenesis, hematopoiesis, germ cell development, tumorigenesis, and aging, with a specific emphasis on findings obtained from the use of zebrafish as a model system. Our comprehensive review highlights the importance of zebrafish in enhancing our understanding of the functions of DNA repair systems at the organismal level and paves the way for future investigations in this field.

Nutritional and immunological evaluation of Nannochloropsis oculata as a potential Nile tilapia-aquafeed supplement

Nannochloropsis oculata (N. oculata) is a marine microalga containing bioactive compounds and a high omega-3 polyunsaturated fatty acid (ω-3 PUFAs). Therefore, it is very promising for nutraceutical and the functional food industry applications. Three groups of Nile tilapia (forty-five fish/group) were fed on basal diets or diets containing 5% (N5) or 10% (N10) of the microalga N. oculata for seven weeks. Fish growth performance, proximate composition, and lipid (fatty acids/ FAs and lipoproteins) profile were estimated. In addition, the expression pattern of some lipid metabolism and immune-relevant genes were assessed. An enhancement in whole body crude protein and growth indices of Nile tilapia was observed on both the supplemented groups N5 and N10. Higher levels of high-density lipoproteins (HDL); and lower levels of the low-density lipoproteins (LDL) were evident in both supplemented groups, while the cholesterol and triglycerides (TG) levels were similar among groups. Ω-3 PUFAs were the significant FAs profile of tilapia fed on N. oculata-supplemented diets in terms of eicosapentaenoic acid, docosahexaenoic acid, and n3/n6 ratio. Concerning the gene expression pattern, heat-shock protein70, glutathione-S-transferase, glutathione peroxidase, and interleukin-1β (IL-1β) were elevated significantly in both supplemented groups. IL-10 is only upregulated in the N10 group. The lipid metabolism-related gene expression showed downregulation of only fatty acid synthase (FAS) in both supplemented groups, with no statistical changes in Peroxisome proliferator-activated receptor alpha (PPARα). Tumor necrosis factor-α (TNF-α), Transforming growth factor-β1 (TGF-β1), and the apoptotic related genes [caspase3 and Proliferating cell nuclear antigen (PCNA)] showed insignificant changes among groups. The histopathological examination of the intestine, liver, and spleen supports our findings and confirms the benefits and safeness of N. oculata dietary inclusion. Collectively, N. oculata is a very promising nutraceutical for improving fish health and sustainability of aquaculture production.

Novel Animal Model of Limbal Stem Cell Deficiency Induced by Forcing Eye-Open at Birth

PURPOSE

The aim of this study was to develop a rat model of limbal stem cell deficiency (LSCD) by forcing eye-open at birth (FEOB).

METHODS

A total of 200 Sprague-Dawley neonatal rats were randomly divided into the control group and the experimental group, which received eyelid open surgery on postnatal day 1 (P1). Observation time points were defined as P1, P5, P10, P15, and P30. Slit-lamp microscope and corneal confocal microscope were used to observe the clinical features of the model. The eyeballs were collected for hematoxylin and eosin staining and periodic acid-Schiff staining. Proliferating cell nuclear antigen, CD68/polymorphonuclear leukocytes, and cytokeratin 10/12/13 immunostaining were performed, while the ultrastructure of the cornea was observed by scanning electron microscopy. Real-time polymerase chain reactions (PCRs), western blot, and immunohistochemical staining of activin A receptor-like kinase-1/5 were used to analyze the possible pathogenesis.

RESULTS

FEOB could successfully induce the typical manifestations of LSCD, including corneal neovascularization, severe inflammation, and corneal opacity. In the FEOB group, goblet cells could be detected in the corneal epithelium by periodic acid-Schiff staining. The expression of cytokeratins was also different between the 2 groups. Furthermore, proliferating cell nuclear antigen immunohistochemical staining revealed the weak proliferation and differentiation ability of limbal epithelial stem cells in the FEOB group. Real-time PCRs, western blot, and immunohistochemical staining of activin A receptor-like kinase-1/activin A receptor-like kinase-5 in the FEOB group showed different expression patterns than those of the control group.

CONCLUSIONS

FEOB in rats induces ocular surface changes resembling LSCD in humans, representing a novel model of LSCD.

DNA repair genes play a variety of roles in the development of fish embryos

Embryogenesis is one of the most important life stages because it determines an organism's healthy growth. However, embryos of externally fertilizing species, such as most fish, are directly exposed to the environment during development and may be threatened by DNA damaging factors (pollutants, UV, reactive oxygen species). To counteract the negative effects of DNA fragmentation, fish embryos evolved complex damage response pathways. DNA repair pathways have been extensively studied in some fish species, such as zebrafish (Danio rerio). Our literature review, on the other hand, revealed a paucity of knowledge about DNA damage response and repair in non-model aquaculture fish species. Further, several pieces of evidence underlie the additional role of DNA repair genes and proteins in organogenesis, spatiotemporal localization in different tissue, and its indispensability for normal embryo development. In this review, we will summarize features of different DNA repair pathways in course of fish embryo development. We describe how the expression of DNA repair genes and proteins is regulated during development, their organogenetic roles, and how the expression of DNA repair genes changes in response to genotoxic stress. This will aid in addressing the link between genotoxic stress and embryo phenotype. Furthermore, available data indicate that embryos can repair damaged DNA, but the effects of early-life stress may manifest later in life as behavioral changes, neoplasia, or neurodegeneration. Overall, we conclude that more research on DNA repair in fish embryos is needed.

Responses of hematopoietic cells after ionizing-irradiation in anemic adult medaka (Oryzias latipes)

PURPOSE

Hematopoietic tissues of vertebrates are highly radiation sensitive and the effects of ionizing radiation on the hematopoiesis have been studied in mammals and teleosts for decades. In this study, radiation responses in the kidney, the main hematopoietic organ in teleosts, were investigated in Japanese medaka (Oryzias latipes), which has been a model animal and a large body of knowledge has been accumulated in radiation biology.

METHODS

Kidney, the main hematopoietic tissue of adult medaka fish, was locally irradiated using proton and carbon ion beams irradiation system of Takasaki Ion Accelerator for Advanced Radiation Application (TIARA), QST, and the effects on peripheral blood cells and histology of the kidney were investigated.

RESULTS

When only kidneys were locally irradiated with proton or carbon ion beam (15 Gy), the hematopoietic cells in the irradiated kidney and cell density in the peripheral blood decreased 7 days after the irradiation in the same manner as after the whole-body irradiation with γ-rays (15 Gy). These results demonstrate that direct irradiation of the hematopoietic cells in the kidney induced cell death and/or cell cycle arrest and stopped the supply of erythroid cells. Then, the cell density in the peripheral blood recovered to the control level within 4 days and 7 days after the γ-ray and proton beam irradiation (15 Gy), respectively, while the cell density in the peripheral blood did not recover after the carbon ion beam irradiation (15 Gy). The hematopoietic cells in the irradiated kidneys temporarily decreased and recovered to the control level within 21 days after the γ-ray or proton beam irradiation (15 Gy), while it did not recover after the carbon ion beam irradiation (15 Gy). In contrast, the recovery of the cell density in the peripheral blood delayed when anemic medaka were irradiated 1 day after the administration of phenylhydrazine. With and without γ-ray irradiation, a large number of hematopoietic cells was still proliferating in the kidney 7 days after the anemia induction.

CONCLUSIONS

The results obtained strongly suggest that the hematopoietic stem cells in medaka kidney prioritize to proliferate and increase peripheral blood cells to eliminate anemia, even when they are damaged by high-dose irradiation.

The proliferating cell nuclear antigen (PCNA) is a potential proliferative marker in oyster Crassostrea gigas

Proliferating cell nuclear antigen (PCNA) is a crucial eukaryotic replication accessory factor in the regulation of DNA synthesis, which is always used as a proliferation marker for haematopoiesis in vertebrates. In the present study, a homologue of PCNA (named as CgPCNA) with a conserved N-terminal PCNA domain and a C-terminal PCNA domain was identified from oyster Crassostrea gigas. The deduced amino acid sequence of CgPCNA shared 85.4% and 86.6% similarities with the PCNAs identified in Mus musculus and Homo sapiens, respectively. CgPCNA was firstly clustered with PCNAs from molluscs, and then with PCNAs from arthropods to form a group falling into the invertebrate clade in the phylogenic tree. The mRNA transcripts of CgPCNA were detected in all tested tissues with higher expression level in gonad, gills and haemolymph. They were also detected in granulocytes, semi-granulocytes and agranulocytes with no significant differences, but the protein level of CgPCNA in agranulocytes was significantly higher (3.67-fold, p < 0.05) than that in granulocytes. In the haemocytes, CgPCNA was mainly distributed in the nucleus and less in the cytoplasm of haemocytes. CgPCNA protein was observed at the tubule lumen regions of gills vessels, and especially colocalized with the EdU signals. After lipopolysaccharide (LPS) and Vibrio splendidus stimulation, the expression level of CgPCNA mRNA in haemocytes was significantly (p < 0.05) up-regulated at 6 h and 12 h, which was 13.87-fold and 3.89-fold of that in control, respectively. In the oysters treated with the recombinant protein CgAstakine (rCgAstakine), the protein abundance of CgPCNA was enhanced in agranulocytes and gills, while no significant change was observed in semi-granulocytes and granulocytes. These results collectively indicated that CgPCNA was highly expressed in the newborn agranulocytes and the potential haematopoietic sites, and it might be applied as a marker for haemocytes proliferation in oysters.

Low concentrations of 4-ABP promote liver carcinogenesis in human liver cells and a zebrafish model

4-Aminobiphenyl (4-ABP) is a human bladder cancer carcinogen found in the manufacture of azo dyes and the composition of cigarette smoke in the environment. To determine whether low concentrations of 4-ABP induced or promote liver carcinogenesis and investigate the underlying mechanism, we have established the liver cell carcinogenesis model in human liver cell lines and zebrafish to evaluate liver cancer development associated with long-term exposure to low concentrations of 4-ABP. Results show that repeated 4-ABP exposure promoted cellular proliferation and migration via the involvement of ROS in Ras/MEK/ERK pathway in vitro. Also, 4-ABP (1, 10, and 100 nM) induces hepatocellular carcinoma (HCC) formation in HBx, Src (p53^-/-) transgenic zebrafish at four months of age and in wild-type zebrafish at seven months of age. In addition, we observed a correlation between the Ras-ERK pathway and 4-ABP-induced HCC in vitro and in vivo. Our finding suggests low concentrations of 4-ABP repeated exposure is a potential risk factor for liver cancer. To our knowledge, this is the first report on the promotion of liver carcinogenesis in human liver cells and zebrafish following 4-ABP exposure.

Neuron-Radial Glial Cell Communication via BMP/Id1 Signaling Is Key to Long-Term Maintenance of the Regenerative Capacity of the Adult Zebrafish Telencephalon

The central nervous system of adult zebrafish displays an extraordinary neurogenic and regenerative capacity. In the zebrafish adult brain, this regenerative capacity relies on neural stem cells (NSCs) and the careful management of the NSC pool. However, the mechanisms controlling NSC pool maintenance are not yet fully understood. Recently, Bone Morphogenetic Proteins (BMPs) and their downstream effector Id1 (Inhibitor of differentiation 1) were suggested to act as key players in NSC maintenance under constitutive and regenerative conditions. Here, we further investigated the role of BMP/Id1 signaling in these processes, using different genetic and pharmacological approaches. Our data show that BMPs are mainly expressed by neurons in the adult telencephalon, while id1 is expressed in NSCs, suggesting a neuron-NSC communication via the BMP/Id1 signaling axis. Furthermore, manipulation of BMP signaling by conditionally inducing or repressing BMP signaling via heat-shock, lead to an increase or a decrease of id1 expression in the NSCs, respectively. Induction of id1 was followed by an increase in the number of quiescent NSCs, while knocking down id1 expression caused an increase in NSC proliferation. In agreement, genetic ablation of id1 function lead to increased proliferation of NSCs, followed by depletion of the stem cell pool with concomitant failure to heal injuries in repeatedly injured mutant telencephala. Moreover, pharmacological inhibition of BMP and Notch signaling suggests that the two signaling systems cooperate and converge onto the transcriptional regulator her4.1. Interestingly, brain injury lead to a depletion of NSCs in animals lacking BMP/Id1 signaling despite an intact Notch pathway. Taken together, our data demonstrate how neurons feedback on NSC proliferation and that BMP1/Id1 signaling acts as a safeguard of the NSC pool under regenerative conditions.

Quantifying endothelial cell proliferation in the zebrafish embryo

Introduction: Endothelial cell (EC) proliferation is a fundamental determinant of vascular development and homeostasis, and contributes to cardiovascular disease by increasing vascular permeability to blood-borne lipoproteins. Rodents have been traditionally used to analyse EC proliferation mechanisms in vascular health and disease; however, alternative models such as the zebrafish embryo allow researchers to conduct small scale screening studies in a physiologically relevant vasculature whilst reducing the use of mammals in biomedical research. In vitro models of EC proliferation are valuable but do not fully recapitulate the complexity of the in vivo situation. Several groups have used zebrafish embryos for vascular biology research because they offer the advantages of an in vivo model in terms of complexity but are also genetically manipulable and optically transparent. Methods: Here we investigated whether zebrafish embryos can provide a suitable model for the study of EC proliferation. We explored the use of antibody, DNA labelling, and time-lapse imaging approaches. Results: Antibody and DNA labelling approaches were of limited use in zebrafish due to the low rate of EC proliferation combined with the relatively narrow window of time in which they can label proliferating nuclei. By contrast, time-lapse imaging of fluorescent proteins localised to endothelial nuclei was a sensitive method to quantify EC proliferation in zebrafish embryos. Discussion: We conclude that time-lapse imaging is suitable for analysis of endothelial cell proliferation in zebrafish, and that this method is capable of capturing more instances of EC proliferation than immunostaining or cell labelling alternatives. This approach is relevant to anyone studying endothelial cell proliferation for screening genes or small molecules involved in EC proliferation. It offers greater biological relevance than existing in vitro models such as HUVECs culture, whilst reducing the overall number of animals used for this type of research.

Effects of RAC1 on Proliferation of Hen Ovarian Prehierarchical Follicle Granulosa Cells

Simple Summary

The growth and development of ovary follicles is an intricate, highly organized process involving many local intra-ovarian factors. Ras-related C3 botulinum toxin substrate1 (RAC1) is speculated to be associated with prehierarchical follicle development of hen ovaries. The current study initially revealed RAC1 mRNA to be expressed in varied-size follicles and stroma and its expression levels in the prehierarchical follicles of 1.0–3.9 mm, 6.0–6.9 mm and 7.0–8.0 mm in diameter were remarkably higher than the other groups. Moreover, RAC1 protein was mainly expressed in the oocytes and granulosa cells (GC), as well as in stromal tissues of the follicles. To understand the exact roles of the RAC1 gene in regulation of follicular GC proliferation and differentiation, siRNA interference and overexpression of the RAC1 gene were conducted. Our experiments demonstrated that the RAC1 gene can significantly promote the expression of mRNA and proteins of FSHR, CCND2, CYP11A1, PCNA and StAR genes in GC and directly elevate the proliferation of GC in vitro. These results indicated RAC1 played a crucial role in regulation of GC proliferation and differentiation and steroidogenesis during the development of prehierarchical follicles. This study provided a base for elucidating the molecular mechanisms underlying the biological effect of RAC1 on the hen ovary follicle growth and development.

Abstract

RAC1 belongs to the small G protein Rho subfamily and is implicated in regulating gene expression, cell proliferation and differentiation in mammals and humans; nevertheless, the function of RAC1 in growth and development of hen ovarian follicles is still unclear. This study sought to understand the biological effects of RAC1 on granulosa cell (GC) proliferation and differentiation of hen ovarian prehierarchical follicles. Firstly, our results showed expression levels of RAC1 mRNA in the follicles with diameters of 7.0–8.0 mm, 6.0–6.9 mm and 1.0–3.9 mm were greater than other follicles (p < 0.05). The RAC1 protein was mainly expressed in oocyte and its around GCs and stromal tissues of the prehierarchical follicles by immunohistochemistry. Further investigation revealed the RAC1 gene remarkably enhanced the mRNA and protein expression levels of FSHR (a marker of follicle selection), CCND2 (a marker of cell-cycle progression and GC differentiation), PCNA (a marker of GC proliferation), StAR and CYP11A1 (markers of GC differentiation and steroidogenesis) (p < 0.05). Furthermore, our data demonstrated siRNA interference of RAC1 significantly reduced GC proliferation (p < 0.05), while RAC1 gene overexpression enhanced GC proliferation in vitro (p < 0.05). Collectively, this study provided new evidence that the biological effects of RAC1 on GC proliferation, differentiation and steroidogenesis of chicken ovary follicles.

Determination of the roles of GREM1 gene in granulosa cell proliferation and steroidogenesis of hen ovarian prehierarchical follicles

Gremlin genes are known members of the DAN family of bone morphogenetic protein (BMP) antagonists, but their functions and regulatory mechanisms in ovarian follicular development of chicken remain unknown. The current study was designed to investigate the mRNA expression patterns of gremlin1 gene (GREM1) and its protein location in the follicles sampled, and to explore the biological effect of GREM1 on the prehierarchical follicular development. This work revealed that chicken GREM1 mRNA exhibits a constant expression level across all the prehierarchical follicles (PFs) from 1-4 mm to 7-8 mm in diameter, and the preovulatory follicles (from F6 to F1) by using RT-qPCR (P > 0.05). The GREM1 protein is predominantly expressed in the oocytes and granulosa cells (GCs) of the PFs by immunohistochemistry. Furthermore, our data demonstrated that siRNA-mediated knockdown of GREM1 in the GCs resulted in a significant reduction in cell proliferation (P < 0.001); conversely, overexpression of GREM1 in the GCs led to a remarkable increase in cell proliferation (P < 0.001). Interestingly, the expression levels of proliferating cell nuclear antigen (PCNA) and cyclin D2 (CCND2) mRNA and proteins were notably increased when GREM1 expression was upregulated in the GCs (P < 0.01), however, the expression levels of CYP11A1 and StAR were markedly downregulated (P < 0.01). The current results showed that GREM1 gene plays a stimulatory role in GC proliferation during growth and development of the prehierarchical follicles in vitro but an inhibitory role in GC differentiation and steroidogenesis of the hen ovary follicles.

Unsupervised generative and graph representation learning for modelling cell differentiation

Using machine learning techniques to build representations from biomedical data can help us understand the latent biological mechanism of action and lead to important discoveries. Recent developments in single-cell RNA-sequencing protocols have allowed measuring gene expression for individual cells in a population, thus opening up the possibility of finding answers to biomedical questions about cell differentiation. In this paper, we explore unsupervised generative neural methods, based on the variational autoencoder, that can model cell differentiation by building meaningful representations from the high dimensional and complex gene expression data. We use disentanglement methods based on information theory to improve the data representation and achieve better separation of the biological factors of variation in the gene expression data. In addition, we use a graph autoencoder consisting of graph convolutional layers to predict relationships between single-cells. Based on these models, we develop a computational framework that consists of methods for identifying the cell types in the dataset, finding driver genes for the differentiation process and obtaining a better understanding of relationships between cells. We illustrate our methods on datasets from multiple species and also from different sequencing technologies.

Characterisation of cholinesterases in mucous secretions and their localisation in epidermis of Labeo rohita and Cirrhinus mrigala

Cholinesterases are multifunctional enzymes and have been associated with diverse physiological functions in addition to their classical role at synapses. In the present study, cholinesterase (ChE) isozymes have been characterised in mucous secretions and their activity has been localised in the epidermis of Labeo rohita and Cirrhinus mrigala. Zymography using specific substrates and inhibitors revealed the presence of two ChE isozymes-ChE-1 and ChE-2. The isozyme ChE-1 was characterised as an atypical butyrylcholinesterase and ChE-2 as a typical acetylcholinesterase in skin mucous secretions of both the fish species. Enzyme histochemical analysis demonstrated the presence of ChE activity in the epidermis of the fish species investigated. In both the fish species, strong ChE activity was observed in the outer-layer epithelial cells, taste buds and neuromasts. The middle and basal layer epithelial cells showed moderate to weak ChE activity. Club cells and mucous goblet cells showed the absence of ChE activity. Characterisation with specific inhibitors indicates that acetylcholinesterase (AChE) was the major cholinesterase type expressed in the epidermis of the two fish species investigated. Immunohistochemical localisation of apoptotic and cell proliferation markers, in addition, revealed high expression of active caspase 3 in the outer-layer epithelial cells, and proliferating cell nuclear antigen (PCNA) in the middle and basal layer epithelial cells. High ChE activity in caspase 3-positive cells in the outer layer of the epidermis and low in PCNA-positive cells in middle and basal layers could point towards the possible involvement of ChEs in cell death and their final extrusion from skin surface.

Characterisation of rainbow trout peripheral blood leucocytes prepared by hypotonic lysis of erythrocytes, and analysis of their phagocytic activity, proliferation and response to PAMPs and proinflammatory cytokines

Rapid and high quality preparation of peripheral blood leucocytes (PBL) is important in fish immunology research and in particular for fish vaccine development, where multiple immune parameters can be monitored on the same fish over time. Fish PBL are currently prepared by density separation using Percoll or Hispaque-1.077, which is time consuming, costly and prone to erythrocyte contamination. We present here a modified PBL preparation method that includes a 20 s hypotonic lysis of erythrocytes and a subsequent separation of PBL from cell debris by a cell strainer. This method is simple, rapid and cost effective. The PBL obtained are similar in cellular composition to those prepared by density separation but have less erythrocyte contamination as demonstrated by FACS analysis and the expression of cell marker genes. Marker gene analysis also suggested that PBL prepared by hypotonic lysis are superior to those obtained by the gradient method in that some high-density cells (certain B cell types and neutrophils) might be lost using the latter. The PBL prepared in this way can proliferate in response to the T cell mitogen PHA, and both lymphoid and myeloid cells can phagocytose fluorescent beads and bacteria, with the latter enhanced by treatment with pro-inflammatory cytokines (IL-1β and IL-6). Furthermore, the PBL can respond to stimulation with PAMPs (LPS, poly I:C) and cytokines (IL-1β and IFNγ) in terms of upregulation of proinflammatory cytokine gene expression. Such data demonstrate the utility of this approach (hypotonic lysis of erythrocytes) for PBL isolation and will enable more studies of their role in disease protection in future immunological and vaccine development research in fish.

Toxicity and non-harmful effects of the soya isoflavones, genistein and daidzein, in embryos of the zebrafish, Danio rerio

Based on the assumed oestrogenic and apoptotic properties of soya isoflavones (genistein, daidzein), and following the current OECD test-guidelines and principle of 3Rs, we have studied the potential toxicity of phytochemicals on the zebrafish embryos test (ZFET). For this purpose, zebrafish embryos at 2-3 h post-fertilisation (hpf) were exposed to both soya isoflavones (from 1.25 mg/L to 20 mg/L) and assayed until 96 hpf. Lethal and sub-lethal endpoints (mortality, hatching rates and malformations) were estimated in the ZFET, which was expanded to potential gene expression markers, determining the lowest observed effect (and transcriptional) concentrations (LOEC, LOTEC), and the no-observable effect (and transcriptional) concentrations (NOEC, NOTEC). The results revealed that genistein is more toxic (LC50-96 hpf: 4.41 mg/L) than daidzein (over 65.15 mg/L). Both isoflavones up-regulated the oestrogen (esrrb) and death receptors (fas) and cyp1a transcript levels. Most thyroid transcript signals were up-regulated by genistein (except for thyroid peroxidase/tpo), and the hatching enzyme (he1a1) was exclusively up-regulated by daidzein (from 1.25 mg/L onwards). The ZFET proved suitable for assessing toxicant effects of both isoflavones and potential disruptions (i.e. oestrogenic, apoptotic, thyroid, enzymatic) during the embryogenesis and the endotrophic larval period.

Effects of the isoflavone genistein in early life stages of the Senegalese sole, Solea senegalensis: role of the Survivin and proliferation versus apoptosis pathways

BACKGROUND

Phytochemical flavonoids are widely distributed in the environment and are derived from many anthropogenic activities. The isoflavone genistein is a naturally occurring compound found in soya products that are habitual constituents of the aquafeeds. This isoflavone possesses oestrogenic biological activity and also apoptotic properties. The present study has been performed to determine the effects of the genistein in the early life stages of the flatfish Senegalese sole during the first month of larval life, and it is focused especially at the metamorphosis, analysing the expression transcript levels and the immunohistochemical protein patterns implicated in the cell proliferation and apoptosis pathways (proliferation cellular/PCNA, anti-apoptosis Survivin/BIRC-5, death receptors/Fas, and Caspases).

RESULTS

The isoflavone genistein induced some temporal disrupting effects in several pro-apoptotic signalling pathways (Fas, CASP-6) at both genistein doses (3 mg/L and 10 mg/L), with increased Fas transcripts and also decreasing CASP-6 mRNA expression levels during metamorphic and post-metamorphic stages of the Senegalese sole. On the other hand, the anti-apoptotic BIRC-5 expression levels were weakly down-regulated with both the highest and lowest doses, but all of these imbalances were stabilised to the baseline levels. In early life stages of the controls, the constitutive basal transcript levels were temporarily and differentially expressed, reaching the highest levels at the pre-metamorphosis phase, as especially in endotrophic larvae (i.e. BIRC-5 mRNA), as well as in the metamorphic (i.e. CASP-6 mRNA) and post-metamorphic stages (i.e. Fas mRNA). In general, through development, continuous and progressive increases in the protein patterns of cell proliferation-PCNA (e.g. mitotic nuclei), anti-apoptotic Survivin (e.g. haematopoietic system, brain, digestive system, gills) and CASP-2 and -6 (e.g. brain, gills, kidney, digestive system, vascular systems, among others) have been immunohistochemically detected. Besides, both the controls and genistein exposed larvae displayed parallel immunostaining protein patterns in the different organ-systems and tissues.

CONCLUSIONS

The transcriptional imbalances observed in the studied genes (BIRC-5, CASP-6, Fas) were only temporarily induced, and apparently no changes in the immunohistochemical protein patterns were detected. Thus, the isoflavone genistein caused not harmful effects in the development and metamorphosis of the Senegalese sole exposed to chronic environmentally relevant concentrations (3 and 10 mg/L).

Liver of the fish Gymnotus inaequilabiatus and nematode larvae infection: Histochemical features and expression of proliferative cell nuclear antigen

Histopathological lesions due to third-larval stage of nematode Brevimulticaecum sp. within the liver of a subpopulation of 31 Gymnotus inaequilabiatus from the Pantanal Region (Brazil) were studied with histochemical and immunohistochemical methods. In 93.5% of fish, livers harboured nematode larvae and the intensity of infection ranged from 8 to 293. In livers with highest number of larvae, the hepatic tissue was occupied primarily by the nematodes. Each larva was encircled by focal inflammatory granulomatous reaction. Within the thickness of the granuloma, three concentric layers were recognized: an inner layer of densely packed epithelioid cells, a middle layer of mast cells (MCs) entrapped in a thin fibroblast-connective mesh and an outer layer of fibrous connective tissue with fibroblasts. Epithelioid cells and fibroblasts within the thickness of the granuloma wall were positive for proliferative cell nuclear antigen (PCNA). Moreover, several hepatocytes in infected liver were immunoreactive to PCNA. Occurrence of rodlet cells and MCs in parenchyma, in close proximity to the encysted nematode larvae and near the blood vessel of infected liver, was observed. Macrophage aggregates (MAs) were numerous within the granulomas and scattered in parenchyma of the infected liver. High quantity of haemosiderin was encountered in MAs and hepatocytes of infected liver.

Gonadal soma controls ovarian follicle proliferation through Gsdf in zebrafish

BACKGROUND

Aberrant signaling between germ cells and somatic cells can lead to reproductive disease and depends on diffusible signals, including transforming growth factor-beta (TGFB) -family proteins. The TGFB-family protein Gsdf (gonadal soma derived factor) controls sex determination in some fish and is a candidate for mediating germ cell/soma signaling.

RESULTS

Zebrafish expressed gsdf in somatic cells of bipotential gonads and expression continued in ovarian granulosa cells and testicular Sertoli cells. Homozygous gsdf knockout mutants delayed leaving the bipotential gonad state, but then became a male or a female. Mutant females ovulated a few oocytes, then became sterile, accumulating immature follicles. Female mutants stored excess lipid and down-regulated aromatase, gata4, insulin receptor, estrogen receptor, and genes for lipid metabolism, vitellogenin, and steroid biosynthesis. Mutant females contained less estrogen and more androgen than wild-types. Mutant males were fertile. Genomic analysis suggests that Gsdf, Bmp15, and Gdf9, originated as paralogs in vertebrate genome duplication events.

CONCLUSIONS

In zebrafish, gsdf regulates ovarian follicle maturation and expression of genes for steroid biosynthesis, obesity, diabetes, and female fertility, leading to ovarian and extra-ovarian phenotypes that mimic human polycystic ovarian syndrome (PCOS), suggesting a role for a related TGFB signaling molecule in the etiology of PCOS. Developmental Dynamics 246:925-945, 2017. © 2017 Wiley Periodicals, Inc.

An Extract from the Plant Deschampsia antarctica Protects Fibroblasts from Senescence Induced by Hydrogen Peroxide

The Antarctic plant Deschampsia antarctica (DA) is able to survive in extreme conditions thanks to its special mechanism of protection against environmental aggressions. In this work, we investigated whether an aqueous extract of the plant (EDA) retains some of its defensive properties and is able to protect our skin against common external oxidants. We evaluated EDA over young human fibroblasts and exposed to H2O2, and we measured cell proliferation, viability, and senescence-associated β-galactosidase (SA-β-Gal). We also tested the expression of several senescence-associated proteins including sirtuin1, lamin A/C, the replicative protein PCNA, and the redox protein thioredoxin 2. We found that EDA promoted per se cell proliferation and viability and increased the expression of anti-senescence-related markers. Then, we selected a dose of H2O2 as an inductor of senescence in human fibroblasts, and we found that an EDA treatment 24 h prior H2O2 exposure increased fibroblast proliferation. EDA significantly inhibited the increase in SA-β-Gal levels induced by H2O2 and promoted the expression of sirtuin 1 and lamin A/C proteins. Altogether, these results suggest that EDA protects human fibroblasts from cellular senescence induced by H2O2, pointing to this compound as a potential therapeutic agent to treat or prevent skin senescence.

Anguilla anguilla intestinal immune response to natural infection with Contracaecum rudolphii A larvae

The European eel, Anguilla anguilla, is a major warm-water fish species cultured in North and South Europe. Seventy-one A. anguilla collected between 2010 and 2015 from the Comacchio lagoons were examined. Fish were infected and damaged by larvae (L3) of the nematode Contracaecum rudolphii A, which were encapsulated within the thickness of the intestinal wall and within the external visceral peritoneum (serosa). Conspicuous granulomas, visible at sites of infection, were arranged in a trilayer, formed by a series of concentric whorls. The cells involved in the immune response and their distribution in the granuloma layers were assessed by immunohistochemical, immunofluorescence, and ultrastructural techniques. The outer part of the granuloma contained macrophages, macrophage aggregates, and mast cells (MCs) scattered among fibroblasts. This layer was vascularized, with degranulation of MCs occurring in close proximity to the capillaries. The middle layer was rich in MCs and fibroblasts. The inner layer, closest to the parasite larva, consisted mainly of dark epithelioid cells, some of which were necrotic. Non-necrotic epithelioid cells formed desmosomes between themselves or with fibroblasts. Within the granulomas, numerous cells of different types were positive to proliferative cell nuclear antigen antibody, indicating a high degree of cellular proliferation around the larvae.

Quercetin-loaded nanomicelles to circumvent human castration-resistant prostate cancer in vitro and in vivo

Prostate cancer is highly prevalent and has become the second leading cause of cancer-related death in men. Its treatment remains a challenge in the clinic, particularly in patients who have advanced to "castration-resistant prostate cancer" (CRPC). Thus, more effective therapeutic strategies are required. Quercetin (QCT) is a natural flavonoid compound that has attracted increasing interest due to its anticancer activity. However, the clinical application of quercetin is largely hampered by its poor water solubility and low bioavailability. The objective of this study was to evaluate the therapeutic potential of novel QCT-loaded nanomicelles (M-QCTs) assembled from DSPE-PEG2000 for prostate cancer treatment. Our results indicated that QCT was efficiently encapsulated into micelles up to 1 mg mL(-1), which corresponds to a 450-fold increase of its water solubility. In vitro studies showed that the half-maximal inhibitory concentration (IC50) value (20.2 μM) of M-QCTs was much lower than free QCT (>200 μM). Thus, M-QCTs were considerably more effective than free QCT in proliferation inhibition and apoptosis induction of human androgen-independent PC-3 cells. Furthermore, M-QCTs showed superior antitumor efficacy and the tumor proliferation rate reduced by 52.03% compared to the control group in the PC-3 xenograft mouse model, possibly due to increased accumulation of M-QCTs at the tumor site by the enhanced permeability and retention (EPR) effect. Collectively, our studies demonstrated that M-QCTs significantly increase drug accumulation at the tumor site and exhibit superior anticancer activity in prostate cancer. Thus, our nanomicelle-based drug delivery system constitutes a promising and effective therapeutic strategy for clinical treatment.

RAP-011 improves erythropoiesis in zebrafish model of Diamond-Blackfan anemia through antagonizing lefty1

Ribosome deficiency in zebrafish leads to defects in erythroid maturation and is reversed by RAP-011 treatment. Identification of lefty1 as a key mediator of erythropoiesis.

Hypoxia Induces a Metabolic Shift and Enhances the Stemness and Expansion of Cochlear Spiral Ganglion Stem/Progenitor Cells

Previously, we demonstrated that hypoxia (1% O₂) enhances stemness markers and expands the cell numbers of cochlear stem/progenitor cells (SPCs). In this study, we further investigated the long-term effect of hypoxia on stemness and the bioenergetic status of cochlear spiral ganglion SPCs cultured at low oxygen tensions. Spiral ganglion SPCs were obtained from postnatal day 1 CBA/CaJ mouse pups. The measurement of oxygen consumption rate, extracellular acidification rate (ECAR), and intracellular adenosine triphosphate levels corresponding to 20% and 5% oxygen concentrations was determined using a Seahorse XF extracellular flux analyzer. After low oxygen tension cultivation for 21 days, the mean size of the hypoxia-expanded neurospheres was significantly increased at 5% O₂; this correlated with high-level expression of hypoxia-inducible factor-1 alpha (Hif-1α), proliferating cell nuclear antigen (PCNA), cyclin D1, Abcg2, nestin, and Nanog proteins but downregulated expression of p27 compared to that in a normoxic condition. Low oxygen tension cultivation tended to increase the side population fraction, with a significant difference found at 5% O₂ compared to that at 20% O₂. In addition, hypoxia induced a metabolic energy shift of SPCs toward higher basal ECARs and higher maximum mitochondrial respiratory capacity but lower proton leak than under normoxia, where the SPC metabolism was switched toward glycolysis in long-term hypoxic cultivation.

Histopathology and the inflammatory response of European perch, Perca fluviatilis muscle infected with Eustrongylides sp. (Nematoda)

BACKGROUND

The European perch, Perca fluviatilis L. is a common paratenic host of dioctophymatid nematodes belonging to the genus Eustrongylides. In this host, once infected oligochaetes, which serve as the first intermediate host, are ingested, Eustrongylides migrates through the intestine and is frequently encountered within the musculature, free within the body cavity, or encapsulated on the viscera. The current study details the first Italian record of Eustrongylides sp. with larvae reported in the muscle of P. fluviatilis.

METHODS

Uninfected and nematode-infected muscle tissues of perch were fixed and prepared for histological evaluation and electron microscopy. Some sections were subjected to an indirect immunohistochemical method using anti-PCNA, anti-piscidin 3 and anti-piscidin 4 antibodies.

RESULTS

A total of 510 P. fluviatilis (TL range 15-25 cm) from Lake Trasimeno, Perugia were post-mortemed; 31 individuals had encysted nematode larvae within their musculature (1-2 worms fish(-1)). Histologically, larvae were surrounded by a capsule with an evident acute inflammatory reaction. Muscle degeneration and necrosis extending throughout the sarcoplasm, sarcolemmal basal lamina, endomysial connective tissue cells and capillaries was frequently observed. Within the encapsulating reaction, macrophage aggregates (MAs) were seen. Immunohistochemical staining with the proliferating cell nuclear antigen (PCNA) revealed numerous PCNA-positive cells within the thickness of the capsule and in the immediate vicinity surrounding Eustrongylides sp. larvae (i.e. fibroblasts and satellite cells), suggesting a host response had been initiated to repair the nematode-damaged muscle. Mast cells (MCs) staining positively for piscidin 3, were demonstrated for the first time in response to a muscle-infecting nematode. The piscidin 3 positive MC's were seen principally in the periphery of the capsule surrounding the Eustrongylides sp. larva.

CONCLUSIONS

A host tissue response to Eustrongylides sp. larvae infecting the musculature of P. fluviatilis was observed. Numerous fibroblasts, MAs and MCs were seen throughout the thick fibroconnectival layer of the capsule enclosing larvae. PCNA positive cells within the capsule suggest that host repair of nematode damaged muscle does occur, while the presence of the antimicrobial peptide piscidin 3 is shown for the first time. This is first report of Eustrongylides sp. in an Italian population of P. fluviatilis.

The epigonal organ and mature pole of the testis in the recreationally fished blue shark (Prionace glauca): histochemico-functional correlates

The exact role of the immune system in normal spermatogenesis is poorly understood. The attachment, however, of the lymphomyeloid epigonal organ specifically to the testis's mature pole in many shark species is a curious finding. Unlike the histology of the lymphomyeloid tissues of many other elasmobranchs, the epigonal organ leukocytes of wild-caught blue shark (Prionace glauca), besides exhibiting extensive nuclear heterogeneity, contain some of the largest known granules ever seen in vertebrate white blood cells. It was previously shown that the blue shark epigonal organ remains unremarkable and functionally unchanged despite cestode parasites embedded into its surface, suggesting that it might have other functions in addition to microbial defense. We show here that Prionace epigonal leukocytes shed their granule-laden cytoplasm into the cyst resorption zone (RZ) of the testis, i.e. the region separating the spermatogenic tissue from the epigonal organ, as they begin to migrate into the RZ. Using the immunoreactivity of the conserved transcription factor (proliferating cell nuclear antigen) as marker, it is shown that the granule-lacking leukocytes exclusively infiltrated spermatozoal cysts leftover after the wave of wide-spread multinuclear cell death in summer-breeding males in a seasonally dependent manner. By contrast, Prionace caught 2 months later showed fully recovered testes containing numerous completely intact spermatozoal cysts. Conversely, degenerating immature spermatids were gradually phagocytized by their accompanying Sertoli cells, and leukocytes did not infiltrate such cysts. The autoimmune response described here resembles in every aspect the testicular autoimmune response induced experimentally in a teleost fish. These observations suggest functional adaptation of shark leukocytes in response to specific changes in the testicular microenvironment.

KCTD10 is critical for heart and blood vessel development of zebrafish

KCTD10 is a member of the PDIP1 family, which is highly conserved during evolution, sharing a lot of similarities among human, mouse, and zebrafish. Recently, zebrafish KCTD13 has been identified to play an important role in the early development of brain and autism. However, the specific function of KCTD10 remains to be elucidated. In this study, experiments were carried out to determine the expression pattern of zebrafish KCTD10 mRNA during embryonic development. It was found that KCTD10 is a maternal gene and KCTD10 is of great importance in the shaping of heart and blood vessels. Our data provide direct clues that knockdown of KCTD10 resulted in severe pericardial edema and loss of heart formation indicated by morphological observation and crucial heart markers like amhc, vmhc, and cmlc2. The heart defect caused by KCTD10 is linked to RhoA and PCNA. Flk-1 staining revealed that intersomitic vessels were lost in the trunk, although angioblasts could migrate to the midline. These findings could be helpful to better understand the determinants responsible for the heart and blood vessel defects.

Analysis of germ cell proliferation, apoptosis, and androgenesis in the Lake Van fish (Chalcalburnus tarichi) during testicular development

In the present study, the testis histology, gonadosomatic index (GSI), germ cell proliferation and apoptosis, and the plasma 11-ketotestosterone (11-KT) and testosterone (T) levels of male Chalcalburnus tarichi were analyzed. According to the histological examinations of the specimens that were caught between February 2009 and January 2010, three testicular stages were determined. Those stages were as follows: (1) recrudescence or prespawning (July-April), (2) spawning (May-June), and (3) postspawning (July). It was observed that the GSI increased gradually, starting from the recrudescence stage, and it reached peak values at the spawning stage, while the lowest values were in the postspawning. Germ cell proliferation in the testis was detected using a proliferating cell nuclear antigen (PCNA), and germ cell apoptosis was detected by transferase dUTP nick end labeling staining. The germ cell PCNA and apoptosis index values were calculated. It was indicated that germ cell proliferation was observed in all of the testicular stages. The highest germ cell PCNA index (PI) levels were detected in July, August, and September, which then dropped in October and stabilized between February and April. The lowest PI values were detected in the spawning stage (May-June). Germ cell apoptosis was observed in all of the months, and the highest apoptotic index values were detected in August, September, October, May, and June. Plasma 11-KT and T levels were at their highest levels in May and June, and it was detected as stabile in the other months. There was a correlation between GSI, PI, and plasma androgen levels. In conclusion, the present data illustrate testicular development stages for C. tarichi and show changes in the level of GSI and sex steroid biosynthesis through spermatogenesis.

Nuanced but significant: how ethanol perturbs avian cranial neural crest cell actin cytoskeleton, migration and proliferation

Children with fetal alcohol syndrome (FAS) display striking craniofacial abnormalities. These features are proposed to result from perturbations in the morphology and function of cranial neural crest cells (cNCCs), which contribute significantly to the craniofacial complex. While certain pathways by which this may occur have been suggested, precise teratogenic mechanisms remain intensely investigated, as does the question of the teratogenic dose. The present study focused on examining how avian cNCC actin cytoskeleton, migratory distance, and proliferation are affected ex vivo by exposure to ethanol concentrations that simulate maternal intoxication. Chick cNCCs were cultured in 0.2% and 0.4% v/v ethanol. Distances migrated by both ethanol-treated and control cells at 24 and 48 h were recorded. Following phalloidin immunocytochemistry, treated and control cNCCs were compared morphologically and quantitatively. Apoptosis and proliferation in control versus treated cNCCs were also studied. Chick cNCCs cultured in ethanol lost their spindle-like shapes and their ordered cytoskeleton. There was a significant stage-dependent effect on cNCC migration at 24 h (p = 0.035), which was greatest at stage 10 (HH). Ethanol treatment for 48 h revealed a significant main effect for ethanol, chiefly at the 0.4% level. There was also an interaction effect between ethanol dose and stage of development (stage 9 HH). Actin microfilament disruption was quantitatively increased by ethanol at the doses studied while cNCC proliferation was increased but not significantly. Ethanol had no effect on cNCC apoptosis. At ethanol levels likely to induce human FAS, avian cNCCs exhibit various subtle, potentially significant changes in morphology, migration, and proliferation, with possible consequences for fated structures.

Cadmium and copper reduce hematopoietic potential in common carp (Cyprinus carpio L.) head kidney

The effects of cadmium and copper on activity of common carp head kidney hematopoietic tissue were evaluated. The fish were subjected to short-term (3 h, Cd-s and Cu-s) or long-term (4 weeks, Cd-l and Cu-l) exposures to 100% 96hLC₅₀ or 10% 96hLC₅₀, respectively. Head kidneys were isolated weekly from 5 fish of each group for 4 weeks (post-short-term exposure and during long-term exposure). Percentage of early blast cells among the hematopoietic precursors was calculated. Proliferative and apoptotic activity were evaluated using immunocytochemical staining for proliferating cell nuclear antigen (PCNA) and caspase 3, respectively. Hematopoietic activity was calculated as the ratio of proliferating to apoptotic cells. All metal exposures induced an increase in frequency of early blast cells. The frequency of proliferating (PCNA-positive) cells also significantly increased. A considerable and significant increase in the frequency of apoptotic cells was the most pronounced effect of metal exposures. Both short-term and long-term treatments caused similar effects, but in case of Cd exposures, the reaction was more pronounced. All metal exposures reduced hematopoietic potential of fish measured as the ratio of proliferating to apoptotic precursor cell frequency. However, in all cases, hematopoietic activity was higher than 1 showing that the rate of repair of hematopoietic tissue prevailed over destruction.

Establishment of a transgenic zebrafish EF1α:Kaede for monitoring cell proliferation during regeneration

Zebrafish is considered as a versatile experimental animal for various research models from development to diseases. In this study, we report the development of transgenic zebrafish line named as Tg(EF1α:Kaede) that expresses translation elongation factor 1 subunit alpha (EF1α) promoter linked to a fluorescent protein (FP), Kaede for monitoring proliferating cells in during regeneration. It was revealed that about 1.4 kb 5'-flanking region of the EF1α was sufficient for its promoter activity. Expression of Kaede with a property of photo-conversion from green to red was detected in different embryonic stages as well as various organs such as brain, heart, pancreas, intestine, ovary, and fins of adult fish. Cell proliferation pattern during fin regeneration was monitored after amputation of Tg(EF1α:Kaede) caudal fin and results shown that this system is simple and efficient method for detecting proliferating cells during tissue regeneration. Developed Tg(EF1α:Kaede) line has potential to investigate the cell proliferation, regeneration, wound healing capacities after tissue damage and evaluate the therapeutic power of wound healing drugs.

Ssrp1a controls organogenesis by promoting cell cycle progression and RNA synthesis

Tightly controlled DNA replication and RNA transcription are essential for differentiation and tissue growth in multicellular organisms. Histone chaperones, including the FACT (facilitates chromatin transcription) complex, are central for these processes and act by mediating DNA access through nucleosome reorganisation. However, their roles in vertebrate organogenesis are poorly understood. Here, we report the identification of zebrafish mutants for the gene encoding Structure specific recognition protein 1a (Ssrp1a), which, together with Spt16, forms the FACT heterodimer. Focussing on the liver and eye, we show that zygotic Ssrp1a is essential for proliferation and differentiation during organogenesis. Specifically, gene expression indicative of progressive organ differentiation is disrupted and RNA transcription is globally reduced. Ssrp1a-deficient embryos exhibit DNA synthesis defects and prolonged S phase, uncovering a role distinct from that of Spt16, which promotes G1 phase progression. Gene deletion/replacement experiments in Drosophila show that Ssrp1b, Ssrp1a and N-terminal Ssrp1a, equivalent to the yeast homologue Pob3, can substitute Drosophila Ssrp function. These data suggest that (1) Ssrp1b does not compensate for Ssrp1a loss in the zebrafish embryo, probably owing to insufficient expression levels, and (2) despite fundamental structural differences, the mechanisms mediating DNA accessibility by FACT are conserved between yeast and metazoans. We propose that the essential functions of Ssrp1a in DNA replication and gene transcription, together with its dynamic spatiotemporal expression, ensure organ-specific differentiation and proportional growth, which are crucial for the forming embryo.

Proliferative cell nuclear antigen (PCNA) expression in the intestine of Salmo trutta trutta naturally infected with an acanthocephalan

Background

Changes in the production of proliferating cell nuclear antigen (PCNA), a 36 kd protein involved in protein synthesis, within intestinal epithelia can provide an early indication of deviations to normal functioning. Inhibition or stimulation of cell proliferation and PCNA can be determined through immunohistochemical staining of intestinal tissue. Changes in the expression of PCNA act as an early warning system of changes to the gut and this application has not been applied to the fields of aquatic parasitology and fish health. The current study set out to determine whether a population of wild brown trout, Salmo trutta trutta (L.) harbouring an infection of the acanthocephalan Dentitruncus truttae Sinzar, 1955 collected from Lake Piediluco in Central Italy also effected changes in the expression of PCNA.

Methods

A total of 29 brown trout were investigated, 19 of which (i.e. 65.5%) were found to harbour acanthocephalans (5–320 worms fish^-1). Histological sections of both uninfected and infected intestinal material were immunostained for PCNA.

Results

The expression of PCNA was observed in the epithelial cells in the intestinal crypts and within the mast cells and fibroblasts in the submucosa layer which is consistent with its role in cell proliferation and DNA synthesis. The number of PCNA-positive cells in both the intestinal epithelium and the submucosa layer in regions close to the point of parasite attachment were significantly higher than the number observed in uninfected individuals and in infected individuals in zones at least 0.7 cm from the point of parasite attachment (ANOVA, p < 0.05).

Conclusions

An infection of the acanthocephalan D. truttae within the intestinal tract of S. t. trutta effected a significant increase in the number of PCNA positive cells (mast cells and fibroblasts) at the site of parasite attachment when compared to the number of positive cells found in uninfected conspecifics and in tissue zones away from the point of parasite attachment.

Studies of ribonucleotide reductase in crucian carp-an oxygen dependent enzyme in an anoxia tolerant vertebrate

The enzyme ribonucleotide reductase (RNR) catalyzes the conversion of ribonucleotides to deoxyribonucleotides, the precursors for DNA. RNR requires a thiyl radical to activate the substrate. In RNR of eukaryotes (class Ia RNR), this radical originates from a tyrosyl radical formed in reaction with oxygen (O(2)) and a ferrous di-iron center in RNR. The crucian carp (Carassius carassius) is one of very few vertebrates that can tolerate several months completely without oxygen (anoxia), a trait that enables this fish to survive under the ice in small ponds that become anoxic during the winter. Previous studies have found indications of cell division in this fish after 7 days of anoxia. This appears nearly impossible, as DNA synthesis requires the production of new deoxyribonucleotides and therefore active RNR. We have here characterized RNR in crucian carp, to search for adaptations to anoxia. We report the full-length sequences of two paralogs of each of the RNR subunits (R1i, R1ii, R2i, R2ii, p53R2i and p53R2ii), obtained by cloning and sequencing. The mRNA levels of these subunits were measured with quantitative PCR and were generally well maintained in hypoxia and anoxia in heart and brain. We also report maintained or increased mRNA levels of the cell division markers proliferating cell nuclear antigen (PCNA), brain derived neurotrophic factor (BDNF) and Ki67 in anoxic hearts and brains. Electron paramagnetic resonance (EPR) measurements on in vitro expressed crucian carp R2 and p53R2 proteins gave spectra similar to mammalian RNRs, including previously unpublished human and mouse p53R2 EPR spectra. However, the radicals in crucian carp RNR small subunits, especially in the p53R2ii subunit, were very stable at 0°C. A long half-life of the tyrosyl radical during wintertime anoxia could allow for continued cell division in crucian carp.

The regenerating gene iα is overexpressed in atrophic gastritis rats with hypergastrinemia

The role of gastrin on the development of atrophic gastritis (AG) and its relationship with the expression of RegIα  in vivo remain unclear. We established experimental AG in rats by combination administration with sodium salicylate, alcohol, and deoxycholate sodium. The mean score of inflammation in gastric antrum in AG rats was significantly elevated (P < 0.05), while the number of glands dramatically decreased (P < 0.05). In addition, the cell proliferation in gastric glands was increased in experimental AG rats, as determined by immunohistochemistry staining of PCNA and GS II. The level of serum gastrin in AG rats was significantly elevated relative to that of normal rats (P < 0.01). Moreover, the expression of RegIα protein and its receptor mRNA was increased in gastric tissues in AG rats (P < 0.05). Taken together, we demonstrated that the overexpression of Reglα is related with hypergastrinemia in AG rats.

FGF signaling regulates rod photoreceptor cell maintenance and regeneration in zebrafish

Fgf signaling is required for many biological processes involving the regulation of cell proliferation and maintenance, including embryonic patterning, tissue homeostasis, wound healing, and cancer progression. Although the function of Fgf signaling is suggested in several different regeneration models, including appendage regeneration in amphibians and fin and heart regeneration in zebrafish, it has not yet been studied during zebrafish photoreceptor cell regeneration. Here we demonstrate that intravitreal injections of FGF-2 induced rod precursor cell proliferation and photoreceptor cell neuroprotection during intense light damage. Using the dominant-negative Tg(hsp70:dn-fgfr1) transgenic line, we found that Fgf signaling was required for homeostasis of rod, but not cone, photoreceptors. Even though fgfr1 is expressed in both rod and cone photoreceptors, we found that Fgf signaling differentially affected the regeneration of cone and rod photoreceptors in the light-damaged retina, with the dominant-negative hsp70:dn-fgfr1 transgene significantly repressing rod photoreceptor regeneration without affecting cone photoreceptors. These data suggest that rod photoreceptor homeostasis and regeneration is Fgf-dependent and that rod and cone photoreceptors in adult zebrafish are regulated by different signaling pathways.

Dose- and time-dependent expression patterns of zebrafish orthologs of selected E2F target genes in response to serum starvation/replenishment

Targets of E2F transcription factors effectively regulate the cell cycle from worms to humans. Furthermore, the dysregulation of E2F transcription modules plays a highly conserved role in cancers of human and zebrafish. Studying E2F target expression under a given cellular state, such as quiescence, might lead to a better understanding of the conserved patterns of expression in different taxa. In the present study, we used literature searches and phylogeny to identify several targets of E2F transcription factors that are known to be serum-responsive; namely, PCNA, MYBL2, MCM7, TYMS, and CTGF. The transcriptional serum response of zebrafish orthologs of these genes were quantified under different doses (i.e., 0, 0.1, 1, 3, and 10% FBS) and time points (i.e., 6, 24 and 48 hours, h) using quantitative RT-PCR (qRT-PCR) in the zebrafish fibroblast cells (ZF4). Our results indicated that mRNA expression of zebrafish pcna, mybl2, mcm7 and tyms drastically decreased while that of ctgf increased with decreasing serum levels as observed in mammals. These genes responded to serum starvation at 24 and 48 h and to the mitogenic stimuli as early as 6 h except for ctgf whose expression was significantly altered at 24 h. The zebrafish Mcm7 protein levels also were modulated by serum starvation/replenishment. The present study provides a foundation for the comparative analysis of quantitative expression patterns for genes involved in regulation of cell cycle using a zebrafish serum response model.

An immunohistochemical study of gill epithelium cells in the Nile tilapia, Oreochromis niloticus

This study reports the first complete mapping of the gill epithelium in a tilapia species. Different gill epithelial cell types of the Nile tilapia, Oreochromis niloticus L. have been identified and located using different antisera against mammalian proteins and various histochemical techniques: Periodic Acid Schiff (PAS), Alcian Blue pH 1.0, 2.5, 3.5, Giemsa and Grimelius. The results show that the stratified filament epithelium of O. niloticus gill can be divided into two distinct regions, a superficial layer, where pavement, mucous and mitochondria rich cells can be found, and a deep layer, constituted by undifferentiated, myoepithelial-like, granular and neuroendocrine cells. V-ATPase and Na+/K+-ATPase presence allowed the identification of pavement and mitochondria-rich cells, respectively, suggesting that, in O. niloticus, pavement cells are implicated in Na+ uptake, whereas mitochondria-rich cells have a role in Cl- uptake. The use of PAS and Alcian Blue allowed the recognition of different sub-populations of mucous cells that differentiate from a common deeper precursor. Neuroendocrine markers were detected in different cell populations, stating evidence for a neuroendocrine role of mitochondria- rich cells, and suggesting the existence of distinct neural pathways, a putative O2-chemosensory and an ion regulatory pathway. A defence role was attributed to the deep filament epithelium, suggested by the presence of resident giemsa positive- eosinophil granular cells. The antibody raised against proliferating cell nuclear antigen identified two different cell types, the undifferentiated cells and myoepithelial-like cells. In the superficial layer, it is here stated for the first time the existence of vimentin positive support cells.

Identification, mRNA expression and characterization of proliferating cell nuclear antigen gene from Chinese mitten crab Eriocheir japonica sinensis

The sliding clamp proliferating cell nuclear antigen (PCNA) plays important roles in nucleic acid metabolism. In this work, we isolated a PCNA gene (designated as EjsPCNA, accession: FJ483830) by rapid amplification of cDNA ends approach from the Chinese mitten crab Eriocheir japonica sinensis. The full-length cDNA of EjsPCNA consists of 1123 nucleotides with an open-reading frame of 780bp encoding 259 amino acids (28.62kDa) and containing an interdomain connecting loop, C-terminal tail, and center loop. Sequence alignment, phylogenetic analyses, and structure comparison revealed that EjsPCNA is a member of the PCNA family. Real-time RT-PCR results indicate that EjsPCNA is expressed throughout three developmental stages. EjsPCNA mRNA expression levels at the first crab stage are significantly higher than that of the other two stages. Present data showed that the expression levels of EjsPCNA in E. j. sinensis are likely related to proliferation activity of tissues, and suggested that EjsPCNA gene is probably involved in the crabs' early developmental regulation.

[Aristolochic acid induces renal tubular injury and inhibits expression of bone morphogenetic protein-7 mRNA in renal tissue of rats]

OBJECTIVE

To investigate the pathogenic mechanism of aristolochic acid nephropathy (AAN) by observing the renal tubular injury and the change of the expression of bone morphogenetic protein-7 (BMP-7) mRNA in renal tissue of rats induced by aristolochic acid (AA), an active constituent in Caulis Aristolochiae Manshuriensis (CAM).

METHODS

Forty-six male Wistar rats were randomly divided into normal control group (n=20) and AA-treated group (n=26). Rats in AA-treated group were intragastrically administered with AA 20 mg/(kg.d), and rats in control group were treated with equal volume of potable water. At the end of the 4th, 8th and 12th week of administration, the 24 h-urine was collected by metabolic cage for detecting the activity of N-acetyl-beta-D-glucosaminidase (NAG) and the blood samples were obtained from abdominal aorta for detecting serum creatinine (SCr). Pathological change and the degree of injury of the kidneys were observed by microscopy. The expression of proliferative cell nuclear antigen (PCNA) was detected by immunohistochemical method, and mRNA expression of bone morphogenetic protein-7 (BMP-7) in the renal tissue was detected by reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

Compared with the normal control group, the activity of NAG and the ratio of SCr vs body weight were markedly increased in rats of the AA-treated group after treatment (P<0.05 and P<0.01). Pathological section of renal tissue showed that most renal tubules had cloudy swelling, and vacuolar degenerating in tubular epithelial cells, with brush border dropping off, and parts of tubular basement membrane were exposed. The degrees of injuries were aggravated depending on treating time. The tubulointerstitial injury (TI) parameter in rats of AA-treated group was higher than that of the normal control group. The positive expression of PCNA was observed in the damaged tubular cells. The proliferation index of PCNA was significantly increased after 4- and 8-week treatment (P<0.01), but was decreased after 12-week treatment (P<0.05). The mRNA expression of BMP-7 was markedly decreased in the AA-treated group compared with the normal control group after 4-week treatment (P<0.05), and decreased with the extension of treatment time.

CONCLUSION

AA can induce injury of the renal tubules, impair the cell regeneration, and inhibit the expression of BMP-7 mRNA in renal tissue. This may be one of the pathogenic mechanisms of AAN.

Identification and characterization of a novel intraepithelial lymphoid tissue in the gills of Atlantic salmon

In addition to being the respiratory organ in fish, the gills form a barrier against the external milieu. Innate and adaptive immune system components have been detected in the gills, but lymphoid cell accumulations similar to that seen in the mammalian mucosa have not been described. The present investigations revealed cell accumulations on the caudal edge of interbranchial septum at the base of the gill filaments in the Atlantic salmon. Cytokeratin immunohistochemical staining and identification of a basal membrane and desmosome cell junctions by electron microscopy showed that the cell accumulation was located intraepithelially. Major histocompatibility complex (MHC) class II+ cells were detected by immunohistochemistry, and laser capture micro-dissection and subsequent RT-PCR analysis revealed expression of T-cell receptor transcripts in the investigated tissue, suggesting the presence of T cells. The intraepithelial tissue reported here may be a suitable location for immune surveillance of gill infections, as well as a target site for new vaccine approaches and investigations of epithelial immunity. This is the first description of a lymphocyte cell aggregation within a teleostian gill epithelium network, illustrating a phylogenetically early form of leukocyte accumulations in a respiratory organ.

Molecular cloning and characterization of proliferating cell nuclear antigen (PCNA) from Chinese shrimp Fenneropenaeus chinensis

The proliferating cell nuclear antigen gene was cloned from Fenneropenaeus chinensis (FcPCNA). The full-length cDNA sequence of FcPCNA encodes 260 amino acids showing high identity with PCNAs reported in other species. FcPCNA expressed especially high in proliferating tissues of shrimp such as haematopoietic tissue (HPT) and ovary. In order to understand the response of HPT to bacteria and virus challenge, mRNA level of FcPCNA in HPT was analyzed after shrimp were challenged by Vibrio anguillarum and white spot syndrome virus (WSSV). FcPCNA expression in HPT of shrimp was responsive to WSSV and Vibrio challenge, but different expression profiles were obtained after challenge by these two pathogens. The data provide additional information to understand the defense mechanisms of shrimp against virus and bacteria.

Inhibition of Müller glial cell division blocks regeneration of the light-damaged zebrafish retina

The adult zebrafish retina possesses a robust regenerative response. In the light-damaged retina, Müller glial cell divisions precede regeneration of rod and cone photoreceptors. Neuronal progenitors, which arise from the Müller glia, continue to divide and use the Müller glial cell processes to migrate to the outer nuclear layer and replace the lost photoreceptors. We tested the necessity of Müller glial cell division for photoreceptor regeneration. As knockdown tools were unavailable for use in the adult zebrafish retina, we developed a method to conditionally inhibit the expression of specific proteins by in vivo electroporation of morpholinos. We determined that two separate morpholinos targeted against the proliferating cell nuclear antigen (PCNA) mRNA reduced PCNA protein levels. Furthermore, injection and in vivo electroporation of PCNA morpholinos immediately prior to starting intense light exposure inhibited both Müller glial cell proliferation and neuronal progenitor marker Pax6 expression. PCNA knockdown additionally resulted in decreased expression of glutamine synthetase in Müller glia and Müller glial cell death, while amacrine and ganglion cells were unaffected. Finally, histological and immunological methods showed that long-term effects of PCNA knockdown resulted in decreased numbers of Müller glia and the failure to regenerate rod photoreceptors, short single cones, and long single cones. These data suggest that Müller glial cell division is necessary for proper photoreceptor regeneration in the light-damaged zebrafish retina and are consistent with the Müller glia serving as the source of neuronal progenitor cells in regenerating teleost retinas.

An animal study of the effects on p16 and PCNA expression of repeated treatment with high-energy laser and intense pulsed light exposure

BACKGROUND AND OBJECTIVE

Non-ablative skin rejuvenation treatments that involve the use of laser/light sources together with cooling devices have gained much popularity in recent years due to the lack of down time that is associated with them. One important but neglected issue is long-term safety. Does the repeated use of non-ablative skin rejuvenation lead to photoaging? Are we creating another sun-bed phenomenon? Recently, we performed an in vitro study to examine the effect of sub-lethal QS 755 nm lasers on the expression of p16INK4a on melanoma cell lines, and found that sub-lethal laser damage could increase DNA damage, which led to an increase in p16 expression. Our objective was to assess the cutaneous effect of repeated exposure to high-energy lasers and intense pulsed light sources on male Institute of Cancer Research (ICR) mice.

STUDY DESIGN/MATERIALS AND METHODS

Twenty-eight male ICR mice were divided into four groups. Other than the control group, all groups received either laser (585 nm pulsed dye laser or 1,320 nm Nd:YAG laser) or intense pulsed light (IPL) treatment. All four groups were anesthetized with a mixture of Hypnorm/Dormicum before treatment. The animals were irradiated twice a week for 6 months. Signs of toxicity such as mortality and weight loss were checked once a week. Skin tumor formation was evidenced by lesions of greater than 1 mm in diameter that persisted for 2 weeks. At the end of the 6 months, the expression of proliferating cell nuclear antigen (PCNA) and p16 in the mouse skin was determined by immunohistochemical staining and immunoblotting using specific monoclonal antibodies for mouse PCNA and p16. The results were expressed as mean +/- standard error of the mean (SEM). Statistical difference was assessed by multiple ANOVA. A P-value of <0.05 was considered to be significant.

RESULTS

At the end of the 6 months, none of the animals had developed any signs of toxicity such as mortality or weight lost. There was no evidence of tumor formation. There were significant elevations of p16 and PCNA in all treated groups as compared to the control group (ANOVA P < 0.05). This particularly applied to the group that was treated with the 1,320 nm Nd:YAG laser.

CONCLUSION

The repeated use of high-energy laser and intense pulsed light source did not cause any toxicity in mice. The changes in p16 and PCNA imply that further studies are necessary to consider the implications of repeated exposure to longer wavelength radiation in human skin.

Initiation of V(D)J recombination in zebrafish (Danio rerio) ovaries

The assembly of mammalian antigen receptor genes is a lymphoid-specific process. However, rearranged immunoglobulin genes can also be recovered from non-lymphoid tissues of cartilaginous fish. This event, known as germline rearrangement, has been speculated to arise from recombination-activating gene (RAG)-mediated recombination in germ cells. In this report, we demonstrate that zebrafish (Danio rerio) oocytes expressing high levels of RAG-RNA can readily initiate recombination cleavage at immunoglobulin gene loci, providing direct evidence for an ongoing process of attempted germline rearrangement in zebrafish ovaries. This attempted rearrangement is largely unproductive, yielding no accumulation of germline-joined immunoglobulin genes in zebrafish, which is consistent with their general absence in this species. Our data, therefore, substantiate the speculation that RAG might have been derived from a transposase, invading germ cells of ancient species, and later become a dedicated recombinase only expressed in developing lymphocytes.